Certain molecules - belonging to the Unwanted Matter category in reefkeeping - pass through the particle prefilters and even the fine particle filters and the only chance how to remove them from seawater is the protein skimming - which role is therefore irreplaceable.

The graph bellow shows the absorption time behaviour for the most of absorbers (sorbents), which is rather problematic for bellow mentioned reasons:

P1 Time Period - Immediately after the new absorber is applied the absorption rate hits the ceiling and is higher than needed. Zero phosphorus concentration is undesirable - trace phosphorus concentration in seawater is required - more information can be found in related article about phosphorus. Many absorbers also release unwanted matter - often toxic (orange area) - causing sometimes pH value changes as well.

P2 Time Period - In the course of certain time the absorption rate is optimal - phosphorus concentration is held on trace level.

P3 Time Period - From certain moment absorption rate falls gradually. The logical economical dilemma arises - when to proceed with absorber exchange? Particularly at this time period the absorber can also be colonized by various bacteria and if kept too long time in a tank, unwanted biological processes can be initiated.

Summary

Uncontrollable non-linear time behaviour of absorption

Risk of negative influence of seawater chemistry after the application of new absorber

Risk of negative influence of seawater biological environment at the end of absorber life time

We recommendregular water exchange in the amount from 5% for large tanks to 20% for smalltanks monthly. Nevertheless, the best solution is automated continuous waterexchange.

More information about seawater exchange can be found in the articles linked bellow. In simple words, the following shall be considered by all reefkeepers:

Each reef tank is unique, with different depletion rate of nutrients, while marine salt composition is always fixed. Seawater exchange as a sole tool for seawater chemistry maintenance will never work in a long run and cannot replace the role of additives.

Majority of commercial marine salts is enriched with trace and minor elements - boosted salts. This is presented as an advantage - which is not.

Precise dosing of the additives and removers can only be made with preceding precise water analysis. New and steady expanding CS TEST product line currently offers following precise titrimetric test kits for seawater: